Clarification/Definitions: The information addressed in this paper applies to adult and adolescent sexual assault patients. Physical evidence is defined as “any matter, material, or condition, large or small, solid, liquid, or gas, which may be used to determine facts in a given situation” (Fulton & Assid, 2006). Sexual assault is defined as “a sexual offense—including forcible rape, attempted rape, statutory rape, sexual harassment, prostitution, or other unlawful sexual contact and other unlawful behavior intended to result in sexual gratification or profit from sexual activity” (US Department of Justice, 2013).

Evidence collection in sexual assault plays a crucial role in the prosecution of sexual offenders. Sexual assault is usually an un-witnessed crime, and the physical evidence of semen/spermatozoa has historically served as the criterion for confirming sexual intercourse. The courts pay much attention to the positive findings of this type of evidence (Allery et al., 2001) (Sharpe, 1963).

Institutions that provide medico-legal exams to sexual assault victims provide complete exams within a specified time frame. For example, many jurisdictions will offer a complete medico-legal forensic exam within 72 hours of the assault. Although this time limitation, which has come to be known as the 72-hour rule, does not apply to all cases, it is the guideline that is still largely practiced (Ledray, 2010).

Time limitations surrounding evidence collection has increasingly become an area of concern and debate. Many forensic practitioners question the 72-hour rule and have adopted new program policies in an attempt to increase the potential for evidence collection and to provide better outcomes for patients. There is a wide variation in practice from state to state, and even organization to organization, with many programs still using the 72- hour rule for evidentiary exams. The variation in time frame ranges from 24 hours to 168 hours, which is seven days (Ledray, 2010).

Origin of the 72-Hour Rule

It is unclear how the 72-hour rule (in regard to evidence collection) originated. Many expert practitioners suggest the rule was derived from the protocol to prevent sexually transmitted diseases (STDs) (Archambault, 2005). Historically, the window to effectively prevent STDs was within 72 hours following an assault. Experts in the medical and forensic field feel this guideline simply carried over and was applied to other aspects of the exam, including the time allocation for evidence collection (Archambault, 2005) (American College of Emergency Physicians, 1999). Still, other sources emphasize the rule originated due to the increased degradation of DNA after 72 hours (Archambault, 2005). This is not strongly supported with scientific evidence. This issue, however, is only partially responsible for the ongoing debate surrounding the rule. Another element that has contributed greatly to the questioning of time frame expansion is the ever-increasing sophistication of the evidence analysis processes, specifically DNA analysis. Consequently, it makes sense to determine what questions have to be answered when considering a change to the time allocated for evidentiary exams. Can evidence be collected 72 hours following a sexual assault? If evidence is collected after 72 hours, then will the quality and quantity of the DNA obtained be sufficient to produce DNA typing results? Are there other benefits (besides possible evidence recovery and analysis) that should be considered by offering exams past 72 hours?

Importance of DNA Analysis to Evidence Collection

DNA evidence analysis is a powerful crime-fighting tool, particularly in sexual assault and homicide cases (Turman, 2011). In extending the time frame, more items should be considered than simply the time needed to recover evidence. While the recovery of evidence is crucial, that evidence is useless if it cannot be analyzed.

From the moment DNA is retrieved from the protective environment of the body, it becomes fragile and is subject to degradation: the breaking down of DNA into smaller fragments by either chemical or physical means (Turman, 2011). This degradation can have an effect on the ability to obtain a useful result from DNA typing (Rudin & Inman, 2002). New advances in DNA analysis technologies are producing promising results in situations where DNA profiles were previously impossible. With new advanced sensitivity and sophistication, evidence that would have previously been considered inadequate (due to sample size or substantial degradation) can now provide reliable results (Turman, 2011).

When a sample is received, preliminary tests are conducted to determine the state of the DNA. These tests can establish how much total DNA is present, how much of that DNA is human, and the level of degradation of the sample (Rudin & Inman, 2002). Different DNA testing methods require different sample characteristics. Some methods require non-degraded, small samples. Degradation is not a factor in other methods, but larger sample sizes are required. For example, current STR systems are more tolerant of poor quality (Rudin & Inman, 2002). The method Restriction Fragment Length Polymorphism (RFLP) requires a minimum amount of DNA (20,000 to 25,000 bp) with little degradation. PCR-based systems require smaller amounts (0.3 to 0.5 ng) of non-degraded DNA than RFLP (Rudin & Inman, 2002). Various methods and results will be covered under the literature review section.

Practitioners should be aware of the significance of DNA evidence and the evolving changes and availability of technology that could lead to more accurate results (Turman, 2011). This information should play an important role in deciding whether to extend evidence collection times.

Literature Review

In order to help determine best practice, literature reviewed covered: evidentiary time collection guidelines; persistence/recovery of evidence post-assault; and current methods of DNA analysis in sexual assault. A literature search was conducted using CINAHL, PubMed, Medline, DuCat, and Google Scholar. Key search words included: sexual assault; evidence collection time; 72-hour rule; forensic evidence collection; detection of spermatozoa in sexual assault; recovery of spermatozoa after coitus; and DNA analysis in sexual assault. The literature review process also included discussions and interviews with forensic nursing experts and forensic laboratory professionals.

The initial literature search yielded 49 potential articles/sources. However, only 30 articles were pertinent. The dates of publication of the literature ranged from 1970 to 2011. The pertinent literature included research studies and non-research articles (literature reviews, guidelines, expert opinions, etc.). The non-research literature was more prevalent than the research literature, as empirical literature is limited regarding this topic.

Guidelines. Among the retrieved literature were six national policy statements and/or guidelines. As shown in Table 1 (Appendix A), several national guidelines recommend evidence collection up to 72 hours, although only three recognize that collection is possible beyond that point. Those that do suggest time expansion do not specify a cut-off time (i.e. 120 hours). Two of the guidelines recommend collection up to 24 hours. These state that evidence diminishes after 72 hours but do not explicitly state whether it is recommended to collect up to that point or past that time frame. Only two of the guidelines refer to extension of collection time secondary to the advancement of technology but do not refer to any particular analysis methods. None of the guidelines discuss the increased or decreased possibility of evidence collection from various anatomic locations (for example, vaginal sources versus cervical.). While some do not explicitly provide the basis for their guidelines, others state that the guidelines are based upon research, evidence analysis, and practice outcomes. See Table 1 for comparison of time recommendations for evidentiary exams.

Persistence/Recovery of Evidence. Research studies dating as far back as the 1970s confirm that spermatozoa have been recovered inconsistently from the female reproductive track for up to 17 days (Morrison, 1972) (Davies & Wilson, 1972) (Silverman & Silverman, 1978). At the time of these studies, DNA analysis was not available. The important contribution of the older studies to this assessment is the fact that it has long been established that spermatozoa are recoverable well past 72 hours post-coitus/assault.

Morgan and Canton (2008) conducted a descriptive study comparing the findings of cervical os specimens versus vaginal pool specimens in 36 sexual assault victims. They concluded that evidence is present longer in the cervical os than the vaginal pool with possibility of survival up to five days. They also noted, however, that the probability of evidence recovery diminishes when collected after 24 hours (Ricci & Hoffman, 1982).

A representative study of the persistence of prostatic acid phosphatase and/or sperm in 90 patients determined sperm presence was quite variable in relation to time. The authors noted that this variation depends greatly on the method of analysis with gram staining (different laboratories utilized different staining techniques), but revealed the presence of sperm survival up to 72 hours (Ricci & Hoffman, 1982).

In a prospective direct comparison of three different staining methods of 174 cervico-vaginal samples, it was concluded that after a three-day period (72 hours), no spermatozoa were detected with any stain (Allery et al., 2001). In a more recent prospective study utilizing a control group without randomization, the authors noted that previous inability to detect genetic profiles could be attributed to the combination of sperm loss/lysis and technological limitations of standard DNA typing systems (Mayntz-Press et al., 2008). The study utilized the Y-STR method of DNA analysis in three female volunteers. DNA profiles were obtainable five to six, and even seven days, post-coitus, although partial profiles as opposed to full profiles were more likely at the later stages (Mayntz-Press et al., 2008).

Expert opinions of Grispino and Faugno are consistent with the previously reviewed research in that spermatozoa has been recovered for up to seven days (Morrison, 1972) (Davies & Wilson, 1972) (Silverman & Silverman, 1978).

Analysis of Recovered DNA. Spermatozoa are typically the biological material of interest in rape evidence. It has been established that evidence can be recovered past 72 hours, although many jurisdictions only collect evidence within three days (due to the constraints of standard DNA profiling). However, the issue of recovery is no longer the main concern. Instead, the issue becomes whether or not recovered evidence is sufficient to provide definitive DNA typing due to degradation, sample size, mixture, etc. (Turman, 2011). Unfortunately, many times the evidence recovered in the field under real-world conditions is less than ideal and often commingled with a large amount of cells from the alleged victim. This complicates the analysis procedures (Sanders, et al., 2006) (Perlin & Sinelnikov, 2009). New technologies are addressing the issues of degradation, sample size, and mixture samples.

In a largely experimental study, Laser Microdissection (LMD) technology was applied to try to separate cell mixtures to isolate combinations of semen and female buccal epithelial cells (Sanders et al., 2006). The results concluded that LMD separation (both QIAmp and Lyse-N-Go methods) provided clear short tandem repeats (STR) of the male donor with the absence of any alleles from the female donor. This new technique allows mixtures to be effectively separated and analyzed (Perlin & Sinelnikov, 2009). If mixtures can be separated isolating the different component DNA, then target DNA can be analyzed.

Researchers from the Netherlands Forensic Institute conducted a similar study. Laser micro-dissection was used, along with a detection process called Fluorescent In Situ Hybridization (FISH). In the preliminary results, complete DNA profiles were obtained from 20-30 isolated FISH treated male cells (de Leeuw et al., 2011). The new techniques are providing complete DNA profiles from samples that are smaller and many times heterogeneous.

In an article reviewing the Y-STR DNA analysis, the author indicates there is much promise of the successful analysis of samples collected greater than 72 hours post-coitus (Taylor, 2011). Taylor indicates that with further research, the method may document exactly when autosomal DNA analysis fails. If this proves to be accurate, then a guideline would be provided that would determine which DNA method would be more likely to succeed in analysis at different time intervals (Taylor, 2011).

In a collaborative and comparative study involving simulated casework samples, authors tested the efficacy of several protocols of differential DNA extraction obtained from gynecological swabs and processed by multiple labs (Vuichard, 2011). The results were variable, according to lab. An important and notable finding in the results was that greater than 90% of the male DNA was lost after DNA differential extraction. This could pose problems in samples with small amounts of male DNA, such as those collected days after an assault. Included in the authors’ findings was the need for the development and comparative testing of alternative cell-separation techniques. The authors also indicate that analysis procedures allowing access to the minor component of DNA mixtures have future potential to improve the success rate of mixture analysis (Vuichard, 2011).

Another fairly new technology utilizes a quantitative computer interpretation method called TrueAllele. This technology replaces humans with computers in DNA analysis (Perlin, 2010). The technology has been utilized to process very small quantities of damaged DNA such as that recovered from the 9/11 tragedy. It is also reported to be capable of processing large amounts of evidence in just one day (100 items) compared to when humans conduct the analyses, which may result in the analysis of one or two cases analyzed per week. Computer technology has been validated by two peer-reviewed studies. The technology has also been utilized in court testimony (Templeton, 2011). Perlin and Sinelnikov compared the efficacy of the computer-based interpretation (quantitative) in a comparative study to current manual methods (qualitative) by measuring the sensitivity of both methods. The results showed that the qualitative interpretation loses identification probability at low levels of DNA quantities (below 100 pg), but that quantitative methods can provide useful information at very low DNA quantities (10 pg) (2009).

Reported Practice Outcomes. Carr (2011) explains that for the past year, the SANE program at Regions Hospital, St. Paul, MN, has increased the time frame for exams up to 120 hours. The center reported a four percent increase in patient volume between August 15, 2009, and August 15, 2010, with the implementation of the new time frame. Nine of the 222 sexual assault patients received an exam 72-120 hours after the assault. None of the nine cases were evaluated by a crime lab due to multiple contributing factors (non-reports, jurisdictional issues, etc.). The author stated that at this point, the data at one year does not support performing an exam past 72 hours (Carr, 2011). Despite this determination, the team has made the decision to continue to evaluate patients up to 120 hours in order to provide more evidence-based data and to ensure that patients receive appropriate treatments, etc. (Carr, 2011).

In a communication with A. Mitchell (2011) of the Allegheny County Crime Laboratory, very limited information was available regarding collection beyond 72 hours. One sample from a rectal swab collected at 81 hours yielded inconclusive results. Another rectal sample collected at 96 hours yielded negative results. The program is currently performing validation studies on a new technology called an automated sperm detection microscope. Preliminary results involved post-coital samples collected at known times and indicated positive findings from the vaginal orifice up to 90-plus hours. This device should be available for casework samples soon.

Implications for Practice, Policy, and Research

Should medical evidentiary exams be conducted beyond 72 hours following sexual assault? This question has challenged professionals in the specialty for years. Empirical research is sparse on this topic, and much of what is available has focused primarily on the period of time in which biological evidence can be recovered. The ability to analyze that evidence is equally as important as the recovery. Based on this review of the literature, the answer to the question is that currently, the evidence available does not support time expansion past 72 hours. It has been established that: physical evidence can be collected well past 72 hours following assault; there is definite potential that new technologies will provide accurate profiles of what was once considered unsuitable evidence; and research in the area is currently underway. However, we will have to wait for the development of clear evidence to support the determination regarding the proper amount of time to extend the evidence collection in sexual assault cases. The lack of sufficient current evidence does warrant further investigation in order to determine clinical practice guidelines.

It would not be prudent, however, to overlook the humanistic and social components of patient care that must be considered when attempting to resolve the time dilemma. Patient care and outcomes should not just be based strictly upon time frames, analysis of evidence, or the potential for prosecution. The importance of offering an exam in the extended time period also involves the treatment to be received, referrals to prevent morbidity, and the follow-up that is so many times necessary for positive patient outcomes. As Carr (2011) specified, part of the decision to continue providing exams within the time expansion included patient contact and the opportunity to offer services. The care a victim initially receives directly influences recovery.

Since there is a potential criminal component in these cases, removing just one perpetrator from society can prevent future assaults. Consequently, the possibility of evidence collection and analysis in just a few patients holds more weight than just the time frame debate. It has been estimated that timely DNA examination of all sexual assaults could prevent 100,000 stranger rapes in the United States (Wickenheiser, 2004). Scientific procedures in the process of a sexual assault should always be accompanied by qualitative supportive treatment of the patient, and research should also include those specific outcomes (Grispino, 1990).

The question of collection time needs to be resolved, and the need for continuity within guidelines is vital. The following includes applicable issues that were revealed during the review of available data. Also based on the data reviewed, implications and or recommendations for practice are purposed:

While the literature demonstrates that the possibility of positive evidence recovery after 72 hours following sexual assault decreases considerably, there is ample evidence that spermatozoa can be recovered past 72 hours, specifically from the cervix.

The available evidence also indicates that the degradation of evidence obtained after 72 hours can result in problematic analysis. Standard DNA typing systems are historically unable to discern the male donor profile after 3 days or less post-coitus (Mayntz-Press, 2008). However, new methods of analysis have produced complete DNA profiles with low DNA samples from male perpetrators (Perlin & Sinelnikov, 2009).

There are no clear national guidelines outlining appropriate time limitations, and this results in many mixed messages and no substantial evidence to provide guidance.

National organizations should review the guidelines in view of current advances in DNA analysis and amend the guidelines as appropriate. This is especially important because many organizations look to these national standards for guidance.

Sexual Assault organizations should consider a policy change to provide exams at least up to 72 hours. A guide to determine when to collect evidence (i.e. penetration versus no penetration, drug facilitated cases, etc.) should be devised to provide direction to practitioners and provide cost containment. The current constraints in the systems (backlogs, lack of analysts, etc.) have to be considered in this decision. Ultimately, at this time, the responsibility falls to programs to determine the best decision for practice. After 72 hours, the decision to complete an evidentiary exam may very well need to be based on the history and variables of each case.

Professionals/practitioners involved in sexual assault cases should become familiar with the capabilities/limitations of their local laboratories. If most recent DNA analysis methods are not available (LMD, Y-STR, etc.), then consideration should be given to send the evidence to laboratories that have those capabilities. In addition, consideration should also be given to preserve the evidence in anticipation that the new methods will become available and provide for future analysis. Legislative changes should be pursued in order to address financial issues resulting in backlog of rape kits.

Laboratories should participate (if not already doing so) in the sexual assault response team meetings and consistently provide outcomes of DNA analysis for all sexual assault cases. Steps should be taken to safeguard patient confidentiality and provide informed consent.

Policy review should be conducted on an intermittent basis to review the application of the latest technologies and to determine how those technologies will affect evidence collection methods.

Programs that have implemented collection times beyond the 72-hour time frame are encouraged to share and publish their findings to increase the amount of evidence-based literature available. Methods of analysis should also be provided in positive evidentiary findings to provide guidance in that aspect. Negative findings are equally important to support potential collection time changes. Programs should collaborate to develop a central reporting site for results to be compiled (Wickenheiser, 2004).

Research. Given the global nature of sexual violence and the paucity of research evaluating the recovery of evidence collection time, specifically with more recent analysis technologies, more research should be conducted. Controlled research has shown significant results; however, this research needs to be applied in real-world cases. Future research should include variables that are encountered in actual cases (i.e. victims who have showered, douched, etc.) to indicate how those variables affect evidence. Because few studies have compared the effectiveness of conducting exams after 72 hours, clinicians and researchers are urged to participate in ongoing studies and evaluate new approaches to best practice for sexual assault patients. Also noted in the literature review was a significant lack of evidence regarding the time frame for adequate recovery of semen/spermatozoa after an anal or oral assault. Consequently, research to determine guidelines in those areas is also indicated.

Summary

This review of the literature regarding the time allocation of evidence collection in sexual assault patients continues to raise many questions. Currently, the evidence available does not warrant a change to increase or decrease the 72-hour standard. The impact of advanced DNA analysis in extended evidence collection is promising. More research in this area is warranted, and ongoing review of evidence is imperative in the effort to provide universal best practice guidelines. “The result will be better justice for victims and safer communities” (American College of Emergency Physicians, 1999).

US Department of Justice (2013). A national protocol for sexual assault: Medical forensic examinations, 2nd. Available at: https://www.ncjrs.gov/pdffiles1/ovw/241903.pdf.

National Policy Guidelines: Time Recommendations for Exams/Evidence Collection

Organization
Name

Evidence Collection Time Post-assault

Cut-off time specified?

Recommendations/ Statements

American College of Emergency Physicians (1999)

Within 72 hours

No

Recommends extending time as technology advances

American Academy of Pediatrics (2001)

Up to 72 hours

No

States that current technology allows for exam beyond 72 hour

US Department of Justice on Violence Against Women (2011)

Ideally within 24 hours

No

States yields reduce considerably after 72 hours

The President’s DNA Initiative (2010)

Not specified

No

Recognizes that evidence may be available beyond 72-hour guideline

World Health Organization (WHO)(2009)

Ideally within 24 hours

No

After 72 hours yields are reduced considerably

The National Center for Women and Policing: National Training Manual for Law Enforcement (2001)

Within 72 hours

72 hours (>72hours with exceptions)

Exams should only be offered >72 hours if continued symptoms of pain, bleeding, excessive force and/or ejaculation without cleanup

About the Author

Terri Augspurger is a graduate of Houston Baptist University, where she received her undergraduate degree in Nursing. She received her Masters of Science in Forensic Nursing from Duquesne University. She currently practices as a Forensic Nurse examiner for adults/adolescents and pediatrics for four counties in Florida. In addition to completing evidentiary exams, she also is a contract SANE instructor for the Florida Council Against Sexual Violence (FCASV) and travels throughout the state of Florida educating potential forensic examiners. Terri holds certification through the International Association of Forensic Nurses in the area of adults, adolescents, and pediatrics as a Sexual Assault Nurse Examiner (SANE). She also holds the following credentials through the American College of Forensic Examiners International: Certified Forensic Nurse (CFN) designation and Diplomat of the American Board of Forensic Examiners (DABFE) and Diplomat of the American Board of Forensic Nursing (DABFN). Terri is also a Certified Pediatric Emergency Nurse (CPEN). Terri serves as an active board member for the Florida Sexual Crimes Investigators Association and is also a member in good standing with the International and Florida Chapters of the International Association of Forensic Nurses (IAFN); Florida Council Against Sexual Violence (FCASV); Florida Nurses Association (FNA); and the Emergency Nurses Association (ENA).